Immersion microscope objective lens

Abstract

An immersion microscope object lens including, in order from an object: a first lens group having positive refractive power as a whole, and including a first lens component in which a meniscus lens having a concave surface facing the object and a meniscus lens having a convex surface facing an image are cemented, a second lens component constituted by a single lens having positive refractive power, and a third lens component in which a negative lens and a positive lens are cemented; a second lens group having positive refractive power as a whole, and including a lens component in which a negative lens and a positive lens are cemented; and a third lens group having negative refractive power as a whole.

1. An immersion microscope objective lens, comprising, in order from an object: a first lens group having positive refractive power, and including a first lens component in which a meniscus lens having a concave surface facing the object and a meniscus lens having a convex surface facing an image are cemented, a second lens component being a single lens having positive refractive power, and a third lens component in which a negative lens and a positive lens are cemented;
 a second lens group having positive refractive power, and including a lens component in which a negative lens and a positive lens are cemented; and 
 a third lens group having negative refractive power, and 
 the following conditional expressions being satisfied:
   1 <|r 1 /F|< 50 
   0.1 <|r 2 /F|< 1.5 
   n12 −n 11>0.3 
     n 3 Gp> 1.7 
 
 where n11 denotes a refractive index at the d-line of the meniscus lens having a concave surface facing the object of the first lens component, n12 denotes a refractive index at the d-line of the meniscus lens having a convex surface facing the image of the first lens component, r1 denotes a radius of curvature of a lens surface contacting the immersion liquid of the meniscus lens having a concave surface facing the object of the first lens component, r2 denotes a radius of curvature of a cemented surface of the first lens component, F denotes a focal length of the entire lens system, and n3Gp denotes a refractive index at the d-line of the positive lens disposed closest to the image of the third lens group. 
 
     
     
       2. The immersion microscope objective lens according to  claim 1 , wherein the third lens group comprises, in order from the object: a seventh lens component in which a positive lens and a negative lens are cemented, and which has a meniscus shape having a convex surface facing the object; and an eighth lens component in which a negative lens and a positive lens are cemented, and which has a meniscus shape having a convex surface facing the image, and
 the following conditional expressions are satisfied:
   ν8 p> 41
 
     n 8 p> 1.8 
 
 where ν8p denotes an Abbe number of the positive lens of the eighth lens component, and n8p denotes a refractive index at the d-line of the positive lens of the eighth lens component. 
 
     
     
       3. The immersion microscope objective lens according to  claim 2 , wherein the Abbe number is 41 or more in all the lenses constituting the first lens group to the third lens group. 
     
     
       4. The immersion microscope objective lens according to  claim 1 , wherein the second lens group comprises, in order from the object: a fourth lens component and a fifth lens component in which a negative lens and a positive lens are cemented respectively; and a sixth lens component in which three lenses of a negative meniscus lens, a biconvex lens and a biconcave lens are cemented. 
     
     
       5. The immersion microscope objective lens according to  claim 4 , wherein the third lens group further comprises, in order from the object: a seventh lens component in which a positive lens and a negative lens are cemented, and which has a meniscus shape having a convex surface facing the object; and an eighth lens component in which a negative lens and a positive lens are cemented, and which has a meniscus shape having a convex surface facing the image, and
 the following conditional expressions are satisfied:
   ν8 p> 41
 
     n 8 p> 1.8 
 
 where ν8p denotes an Abbe number of the positive lens of the eighth lens component, and n8p denotes a refractive index at the d-line of the positive lens of the eighth lens component. 
 
     
     
       6. The immersion microscope objective lens according to  claim 5 , wherein the Abbe number is 41 or more in all the lenses constituting the first lens group to the third lens group. 
     
     
       7. An immersion microscope objective lens, comprising, in order from an object: a first lens group having positive refractive power, and including a first lens component in which a meniscus lens having a concave surface facing the object and a meniscus lens having a convex surface facing an image are cemented, and which is disposed closest to the object;
 a second lens group having positive refractive power, and including a lens component in which a negative lens and a positive lens are cemented; and 
 a third lens group having negative refractive power, and 
 an Abbe number of the positive lens disposed closest to the image of the third lens group being greater than 41 and a refractive index at the d-line of the positive lens being greater than 1.8. 
 
     
     
       8. The immersion microscope objective lens according to  claim 7 , wherein the Abbe number is 41 or more in all the lenses constituting the first lens group to the third lens group.